1、Convenient Observation: The position of the LED corresponds to the position of the 2x20 pin connector of for RPi, so the logic level of GPIO can be observed quickly and intuitively. The driving current of the LED is only 0.1mA, so there is no need to worry about affecting the read write state of GPIO. 2、Scope of Application: Terminal block board is applicable to for RPi A+3A+B+2B, 3B, 3B+4B, etc. 3、LED Light: The output or input level of GPIO is high, the LED lights up, the output or input level is low, and the LED goes out. 5V blue, 3.3V red, GPIO green. 4、Easy to Use: Terminal block board module is easy to use, and can be used after being connected. 5、Spacing Size: Terminal spacing is 3.5mm/0.138in, conductor size ranges from 26AWG to 16AWG, and it is small and light.